A Gordon Research Conference on RNA Editing is planned for January 2005 and January 2007 in Ventura, California. This biannual conference is the only regularly scheduled meeting devoted exclusively to RNA editing and RNA modification. The term RNA editing refers to a wide range of enzymatic activities, which specifically alter the primary sequence of a transcript. Mechanistically, there are many different types of editing that alter the sequence of an RNA from that encoded by the gene. By altering the coding capacity of a transcript, RNA editing can generate alternative mRNAs that encode proteins with different biological functions. Strikingly, RNA editing is critical for proper development and/or function of the nervous system in mice, worms, and flies. The variety and extent of RNA modifications are equally astonishing, with almost 100 different nucleosides reported in all types of RNAs. RNA modifications are believed to influence many vital processes, including genetic imprinting, RNA splicing, and the efficiency or fidelity of protein synthesis. Despite the diversity of substrates, mechanisms, and biological consequences, many of the critical theoretical and technical questions for the different types of RNA editing and modification are similar. The 2005 RNA Editing Conference will provide scientists investigating these diverse processes with a unique opportunity to interact at a single meeting in order to discuss new hypotheses and mechanistic paradigms, exchange information about experimental strategies, and initiate collaborations. The meeting will bring together a relatively small group of scientists for five days in a casual setting that fosters informal discussion among participants. Established leaders in the field as well as junior scientists will be invited. Talks will be presented in the mornings and evenings, with the afternoons reserved for informal discussions, recreation, and poster sessions. To promote crossfertilization between the editing and modification communities, the program will be organized in thematic sessions, which will focus on questions of common interest.